From: PO3::"magbeti@GPU.SRV.UALBERTA.CA" "Michael Agbeti" 18-JAN-1996 14:41:22.91 To: Multiple recipients of list DIATOM-L CC: Subj: Biomass vs chl-a: Conversion! In the first place, I am expressing my sincere gratitude for the numerous diatom-list members who responded to my request above. It was more than I expected. Other people on the net are also interested in the outcome, so I want to post it net-wide. My request is specifically as follows. We have total biomass for algal count and want to have it converted to chl-a. This will enable us compare the present data with a similar thing done in the past in the same waterbody, but in which chl-a was used (I guess converted from biomass). For this reason, I only deal with in the infos on total biomass and not on the chl-a content of individual algal cells. NOW TO THE MAIN POINT. In an paper by McCauley and Kalff (1981), that looked the emprirical relationships btn zooplankton and phytoplankton biomass in lakes (most data collected from the literature), they had some lakes for which chl-a (and no biomass (biovolume) was available. For those lakes, they converted chl-a to biomass using the factor (ratio) of 0.01 (Ahlgren 1970). I could not get quick access to Ahlgren (1970). Other related refs: - Nicholls & Dillon (1978) found that the cellular chlorophyll content of algae ranges from 0.1% and 9.7% of fresh weight. - Voros & Padisak (1991) found relative chl-a content of phytoplankton biomass varied btn 0.08% and 1.88% (these are in shallow lakes) Detailed refs: McCauley, E. & J. Kalff, 1981. Empirical relationships between phytoplankton and zooplankton biomass among lakes. Can. J. Fish. Aquat. Sci. 38: 458-4463. Voros, L. & J. Padisak, 1991. Phytoplankton biomass and chl-a in some shallow lakes in central Europe. Hydrobiol. 215: 111-119.. Nicholls, K. & P. J. Dillon, 1978. An evaluation of phosphorus -chlorophyll-phytoplankton relationships for lakes. Int. Rev. ges. Hydrobiol. 63: 141-154. Ahlgren, G. 1970. Limnological studies of Lake Norviken, a eutrophicated Swedish lake. II. Phytoplankton and its production. Schweiz. Z. Hydrol. 32: 353-396. I hope these help. I was given other refs on chla/Carbon ratios but I did not look for the refs, since this is not directly related to the stuff I want. If any one wants those refs e-mail me privately and I will send them to you. Again thanks for your help. Michael.